In our body, some amino acids are changed into metabolic intermediates ... ...

In our body, some amino acids are changed into metabolic intermediates which can enter metabolic cycles. One such example is given below. The example shows the conversion of serine into pyruvate which can be converted to acetyl CoA and enter the Krebs cycle. Compound Y can be best described as:
(A) an amide.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in 28. Amino Acids and Proteins